载锌、无机钙磷控释聚合物纳米粒子改性齿科树脂粘接系统的实验研究

Degradation of dentin bonding interface is the main cause for the failure of adhesive restorations. The ultimate goal in the design of dental adhesives is to protect collagen fibrils of the dentin scaffold from degradation, and to obtain more durable adhesion to dentin. The aim of the study is to incorporate a zinc，calcium- and phosphate-releasing particle: zinc-loaded polymeric nanocarriers (Zn/P(MMA-EDMA-MAA)NPs) and CaP- loaded polymeric nanocarriers (CaP/P(MMA-EDMA-MAA)NPs) into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide zinc、calcium ions or mineral deposition within the resin-dentin bonded interface permitting a controlled ion release rate. First of all, in order to screen the best ratio of Zn/P(MMA-EDMA-MAA)NPs and CaP/P(MMA-EDMA-MAA)NPs incorporating into dental adhesive system，the mechanism of release kinetics and the biological activity of the P(MMA-EDMA-MAA) NPs will be investigated，also the effect of Zn/P(MMA-EDMA-MAA)NPs and CaP/P(MMA-EDMA-MAA)NPs on the degree of conversation of resins adhesive system and the dentin bonding performance will be tested. And then through the ion controlled eleasing experiment, C-terminal telopeptide of type I collagen (ICTP) test, remineralization research in the hybrid layer, and antibacterial experiment, we will discuss the effect of Zn/P(MMA-EDMA-MAA)NPs and CaP/P(MMA-EDMA-MAA)NPs on the inhibiting MMP-mediated dentin collagen degradation, favoring ion exchange for mineral precipitation at the hybrid layer, and antibacterial performance comprehensively, with the purpose of further clarify the mechanism of the novel P(MMA-EDMA-MAA)NPs on the improvement resin dentin bonding stability. Finally, the prospect of clinical application of the novel P(MMA-EDMA-MAA)NPs modified dentin adhesive system will be identified via application in vitro bonding ageing model. This research will provide a new strategy for remineralization of hybrid layer and lay the foundation for the development of novel dental adhesive materials, which can improve the dentin bonding durability.

牙本质粘接界面降解退变是引起粘接修复失败的主要原因。保护粘接界面中裸露的胶原纤维免于降解，促进混合层再矿化，提高粘接耐久性是牙本质树脂粘接系统研发的最终目标。本课题拟选用聚合物纳米粒子P(MMA-EDMA-MAA)，利用其易螯合锌钙磷特性及优异的控释性能，分别构建载锌、无机钙磷的聚合物纳米粒子，并对牙本质树脂粘接系统进行改性。首先研究其释放动力学和生物学性能，并评估其对树脂固化效能以及粘接性能的影响，确立最适应用浓度。进而通过控释动力学实验、酶学实验、再矿化研究、抗菌学实验全面探讨新型聚合物纳米粒子在抑制MMPs介导的胶原纤维降解，促进混合层再矿化以及抗菌性能方面的效应，阐明其增强牙本质粘接界面稳定性的机制，最后通过体外粘接耐久性实验评价载锌、无机钙磷的聚合物纳米粒子改性牙本质树脂粘接系统的应用前景。本课题的完成有助于解决混合层再矿化的难题，为改进及研制新型牙本质树脂粘接材料提供实验依据。

本课题基于树脂-牙本质粘接界面降解退变机制，选用羧基功能化聚合物纳米粒子P(MMA-EDMA-MAA)NPs，利用其易螯合阳离子特性及优异的控释性能，构建载锌聚合物纳米粒子Zn@P(MMA-EDMA-MAA)NPs，并联合无定型纳米磷酸钙颗粒（NACP）以及季铵盐树脂单体（DMAHDM）对牙本质树脂粘接系统进行改性，以期保护粘接界面中裸露的胶原纤维免于降解，强效抗菌以及促进混合层再矿化，提高粘接耐久性。研究首先选用P(MMA-EDMA-MAA)NPs，常温下与ZnCl2溶液自组装构建Zn@P(MMA-EDMA-MAA)NPs并对其微观形貌以及载锌量进行表征鉴定；然后通过离子释放动力学，树脂固化效能，渗透能力以及粘接性能测试，筛选确立Zn@P(MMA-EDMA-MAA)NPs添加至树脂粘接剂最适应用浓度为5 wt%；然后通过酶学免疫实验检测胶原纤维降解产物—I型胶原纤维吡啶交联终肽（ICTP），分析Zn@P(MMA-EDMA-MAA)NPs对脱矿牙本质内源性基质金属蛋白酶（MMPs）介导胶原纤维降解的抑制作用；通过纳米压痕仪检测混合层的纳米显微硬度以及分析混合层Ca/P比值变化，研究Zn@P(MMA-EDMA-MAA)NPs对混合层再矿化的促进作用；通过培养口腔细菌生物膜，检测Zn@P(MMA-EDMA-MAA)NPs改性树脂粘接剂的抗菌性能；最后将5 wt% Zn@P(MMA-EDMA-MAA）NPs与20 wt% NACP以及5 wt% DMAHDM联合应用于树脂粘接剂，研究其抗菌性能，对内源性MMPs的抑制以及促进混合层再矿化作用，通过体外粘接耐久性实验阐明其增强牙本质粘接界面稳定性的机制。研究结果显示Zn@P(MMA-EDMA-MAA)NPs+NACP+DMAHDM可以赋予树脂粘接剂持久强效的抗菌性能，能够显著抑制牙本质内源性MMPs介导的胶原纤维降解，增强混合层底部的显微硬度，促进混合层再矿化，从而提高牙本质粘接耐久性能。研究结论：Zn@P(MMA-EDMA-MAA)NPs+NACP+DMAHDM联合改性牙本质树脂粘接系统可以有效稳定牙本质粘接界面，具有良好的临床应用前景。